Soliton generation via continuous stokes acoustic self-scattering of hypersonic waves in a paramagnetic crystal

Journal Article · Fri Aug 15 04:00:00 EDT 2008 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S1063776108080177· OSTI ID:21241948

Bugay, A N ^[1]

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1. Immanuel Kant State University of Russia (Russian Federation)

A new mechanism is proposed for continuous frequency down-conversion of acoustic waves propagating in a paramagnetic crystal at a low temperature in an applied magnetic field. A transverse hypersonic pulse generating a carrier-free longitudinal strain pulse via nonlinear effects is scattered by the generated pulse. This leads to a Stokes shift in the transverse hypersonic wave proportional to its intensity, and both pulses continue to propagate in the form of a mode-locked soliton. As the transverse-pulse frequency is Stokes shifted, its spectrum becomes narrower. This process can be effectively implemented only if the linear group velocity of the transverse hypersonic pulse equals the phase velocity of the longitudinal strain wave. These velocities are renormalized by spin-phonon coupling and can be made equal by adjusting the magnitude of the applied magnetic field. The transverse structure of the soliton depends on the sign of the group velocity dispersion of the transverse component. When the dispersion is positive, planar solitons can develop whose transverse component has a topological defect of dark vortex type and longitudinal component has a hole. In the opposite case, the formation of two-component acoustic 'bullets' or vortices localized in all directions is possible.

• OSTI ID: 21241948
• Journal Information: Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 2 Vol. 107; ISSN JTPHES; ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CRYSTALS
DISPERSIONS
MAGNETIC FIELDS
NONLINEAR PROBLEMS
PARAMAGNETISM
PHASE VELOCITY
PHONONS
PULSES
SCATTERING
SOLITONS
SOUND WAVES
SPIN
TOPOLOGY